We spoke with the players clubs at both casinos, just to make sure, but no, the physical card doesn't expire, only the points on it. How long those last varies from club to club: At the Palms, it's one year since you last used it and it's the same at Bill's, which is still not part of Caesars' Total Rewards Club. If it was, your points would expire six months after you last used or earned any.
As far as those expiration dates are concerned, Bill's told us that they relate to your Diamond-Tier status, which demands that you earn 11,000 points or more in the calendar year to entitle you to additional rewards and privileges, including at the seven casinos in Las Vegas in the Total Rewards program. Is the expiration date Dec. 31? We ask, as we don't have a Diamond card there and had real difficulty getting through to a Bill's Players Club representative (we kept being directed to Total Rewards, and then often to a recording, which told us they were too busy to answer), so we're not 100 percent convinced about the response we got. Drop us a line if the expiration date on your Bill's card is anything other than the end of the year, and we'll go check this out in person.
As to the Palms, we had more luck. Here, we were told that technically your physical card doesn't expire, in that your account stays active no matter what and only the points expire if you don't use them, but that the style of the card is changed on an annual basis (different color, etc.) Even if your card is past its "expiration" date, i.e., a new design has been issued, it should still work in the machines, but as soon as you need a new one for any reason, you'll be issued with the new style.